The present invention relates to a structure which, upon failure of the lamp of a projector, prevents scattering of broken pieces of the lamp to the exterior of the projector main body.
Recently, a type of projector has become widespread which irradiates light from a lamp upon a picture display device such as a digital micromirror device (DMD) or a liquid crystal display device or the like, and projects a picture which is displayed upon this picture display device upon a screen.
With this type of projector, sometimes for one reason or another the lamp which is used as a light source fails, and may break. Due to this, in order for the user not to be injured by the broken pieces of the lamp, inventions have been disclosed related to a projector or to a projection type display device which is built so that, upon failure of the lamp, the broken pieces do not scatter directly to the exterior.
With the liquid crystal projector described in Japanese Laid-Open Patent Publication 2001-216536, an air flow conduit, an intake aperture, and an exhaust aperture are formed in a lamp unit for cooling the lamp. Furthermore, a plurality of vent portions consisting of metallic plates with holes punched out therefrom are provided in this intake aperture and exhaust aperture of the lamp unit. However, since these vent portions have the structure described above, during use, dust adheres to the holes and the venting characteristic becomes bad, so that it becomes impossible to cool the lamp with good efficiency.
Furthermore, with the projection type display device described in Japanese Laid-Open Patent Publication 2003-344949, an exhaust fan is attached to an exhaust aperture of the light source unit. Due to this, when the lamp breaks, the majority of the broken pieces collide with the inner walls of the duct; but sometimes broken pieces of size greater than or equal to 0.8 mm2, which is defined by a safety standard, are scattered to the exterior of the device at a speed which is almost equal to the speed of the exhaust flow from the exhaust aperture, which is undesirable.
The object of the present invention is to provide a projector with which dust does not collect in an intake aperture or an exhaust aperture for cooling the lamp unit, and moreover with which, upon damage to the lamp, broken pieces of a size greater than that determined by the safety standard are not scattered to the exterior.